DRAFT RECOVERY PLAN FOR THE GIANT GARTER SNAKE (Thamnopsis gigas) Authors Karen J. Miller Kelly Hornaday U.S. Fish and Wildlife Service Sacramento Fish and Wildlife Office and The Giant Garter Snake Recovery Team Prepared for Region 1 U.S. Fish and Wildlife Service (1999) Approved: XXXXXXXXXXXXXXXXXXXXXXXXX Manager, California/Nevada Operations Office, Region 1, U.S. Fish and Wildlife Service Date: XXXXXXXXXXXXXXXXXXXX In memory of George E. Hansen, an extraordinarily talented herpetologist who was dedicated to the conservation of giant garter snakes DISCLAIMER PAGE Recovery plans delineate reasonable actions that are believed to be required to recover and/or protect listed species. Plans are published by the U.S. Fish and Wildlife Service, sometimes prepared with the assistance of recovery teams, contractors, State agencies, and others. Objectives will be attained and any necessary funds made available subject to budgetary and other constraints affecting the parties involved, as well as the need to address other priorities. Recovery plans do not necessarily represent the views, official positions, or approval of any individuals or agencies involved in the plan formulation, other than the U.S. Fish and Wildlife Service. They represent the official position of the U.S. Fish and Wildlife Service only after they have been signed by the Director, Regional Director, or Manager as approved. Approved recovery plans are subject to modification as dictated by new findings, changes in species statuses, and the completion of recovery tasks. LITERATURE CITATION SHOULD READ AS FOLLOWS: U.S. Fish and Wildlife Service. 1999. Draft Recovery Plan for the Giant Garter Snake (Thamnopsis gigas). U.S. Fish and Wildlife Service, Portland, Oregon. ix+ 192 pp. i ACKNOWLEDGMENTS We wish to sincerely thank and gratefully acknowledge the recommendations and assistance from the Giant Garter Snake Recovery Team: Technical Subteam: John Brode, California Department of Fish and Game, Rancho Cordova, CA George Hansen, Consultant Herpetologist, Sacramento, CA Robert Hansen, Editor, Herpetological Review, Clovis, CA Mark Jennings, U.S. Geological Service, Biological Resources Division, San Simeon, CA Norm Scott, U.S. Geological Service, Biological Resources Division, San Simeon, CA Michael Westfall, California Department of Parks and Recreation, Los Gatos, CA Michael Wolder, U.S. Fish and Wildlife Service, Sacramento National Wildlife Refuge, Willows, CA Glenn Wylie, U.S. Geological Service, Biological Resources Division, Dixon, CA David Zezulak, California Department of Fish and Game, Rancho Cordova, CA Stakeholder Subteam: John Beam, California Department of Fish and Game, Los Banos Wildlife Area, Los Banos, CA David Brown, Sacramento-Yolo Mosquito and Vector Control District, Elk Grove, CA Kevin Foerster, U.S. Fish and Wildlife Service, Sacramento National Wildlife Refuge, Willows, CA Bob Herkert, California Rice Industry, Colusa, CA Jeff Jaraczeski and Daniel Keppen, Northern California Water Association, Sacramento, CA Terence Moore, City of Sacramento, Sacramento, CA David Widell, Grassland Water District, Los Banos, CA Olen Zirkel, The Nature Conservancy, Sacramento, CA ii Additional Contributors Ruth Elbert (Tricolored Blackbird Account) John Sargent (White-faced Ibis Account) U.S. Fish and Wildlife Service Sacramento Fish and Wildlife Office Michael Miller (Pacific Flyway Waterfowl Account) U.S. Geological Survey Biological Resources Division, Dixon With apologies to anyone inadvertently left off of this list, we also wish to sincerely thank and gratefully acknowledge the advice, assistance, and comments from the following individuals (U.S. Fish and Wildlife Service personnel in italics): Tiki Baron, Ted Beedy, Brad Bortner, Betsy Bolster, Steve Brueggemann, Kati Buehler, Mike Carpenter, Mike Casazza, Kathleen Christian, Jeanne Clark, Dan Connelly, Marilyn Cundiff, Steve Cordes, Joan Daugherty, Diane Elam, Rosalie Faubion ,Alan Forkey, Ken Fuller, Cay Goude, James Hainline, David Hardt, Dwight Harvey, Larry Host, R. Josh Hoffman, Kevin Hunting, Eric Kelchlin, Bill Lehman, Marla Macoubrie, Darlene McGriff, Tina Menges, Steve Morey, Harry Mossman, John Nagle, Larry Norris, Jo Ann Odemar, Ruth Ostroff, Dan Yparraguire, Dave Patterson, Melanie Paquin, Tom Paulek, Dave Paullin, Bill Perry, Debra Schlafman, David Shuford, Chuck Solomon, Howard Stark, Dan Strait, Kenneth Sturm, Marie Sullivan, Deb Swain, Barbara Tatman, Dennis Taylor, Betty Warne, Alison Willy, Diane Windham, Mike Womack, Dennis Woolington, and Tara Zimmerman. iii EXECUTIVE SUMMARY Current Status: This recovery plan features the federally threatened giant garter snake (Thamnopsis gigas). This species inhabits wetland habitats within the Central Valley of California. Loss and fragmentation of wetland habitats have extirpated the giant garter snake from the majority of its historic range. This recovery plan also considers several species of concern that occur in Central Valley wetlands that benefit from actions taken to recover the giant garter snake. These species include the tricolored blackbird (Agelaius tricolor), white-faced ibis (Plegadis chihi), western pond turtle (Clemmys marmorata), and associated waterfowl. Habitat Requirements and Limiting Factors: The giant garter snake inhabits agricultural wetlands and other waterways such as irrigation and drainage canals, sloughs, ponds, small lakes, low gradient streams, and adjacent uplands in the Central Valley. Because of the direct loss of natural habitat, the giant garter snake relies heavily on rice fields in the Sacramento Valley, but also uses managed marsh areas in Federal National Wildlife Refuges and State Wildlife Areas. There have been only a few recent sightings of giant garter snakes in the San Joaquin Valley. Habitat loss and fragmentation, flood control activities, changes in agricultural and land management practices, predation from introduced species, parasites, water pollution, and continuing threats are the main causes for the decline of this species. Recovery Priority: 2C (full species, high degree of threat, high recovery potential). See Appendix A for how recovery priorities are established for listed species. Recovery Objective: The ultimate goal of this recovery plan is to delist the giant garter snake. Recovery Criteria: Recovery criteria for the giant garter snake are defined for four recovery units in the Central Valley: the Sacramento Valley, Mid-Valley, San Joaquin Valley, and South Valley units. Recovery criteria include: a. Monitoring shows that in 17 out of 20 years, 90 percent of the subpopulations in four recovery units contain both adults and iv young. b. All extant populations within the recovery unit are protected from threats that limit populations. c. Supporting habitat within the recovery unit is adaptively managed and monitored. d. Subpopulations are well connected by corridors of suitable habitat. e. Repatriation (reintroduction) has been successful at a specified number of suitable sites. Actions Needed: 1. Protect existing populations and habitat. 2. Restore populations to former habitat. 3. Survey to determine species distributions. 4. Monitor populations. 5. Conduct necessary research, including studies on demographics, population genetics, and habitat use. 6. Develop and implement incentive programs, and an outreach and education plan. Total Estimated Cost of Recovery: The total estimated cost of recovery for the giant garter snake is broken down by priority of tasks. Certain costs, such as securing and protecting specific habitat areas, have yet to be determined. Priority 1 tasks: $61,048,000 Those actions that must be taken to prevent extinction or prevent the species from declining irreversibly in the foreseeable future. Priority 2 tasks: $950,000 Those actions that must be taken to prevent a significant decline in the species population or habitat quality, or some other significant negative impact short of extinction. Priority 3 tasks: $360,000 All other actions necessary to meet the recovery and conservation v objectives outlined in this recovery plan. Cost of Recovery: $62,358,000 plus additional costs yet to be determined. Date of Recovery: Delisting could be initiated by 2028, if recovery criteria have been met. vi TABLE OF CONTENTS DISCLAIMER PAGE .............................................i ACKNOWLEDGMENTS ......................................... ii EXECUTIVE SUMMARY ........................................iv INTRODUCTION .............................................. 1 Brief Overview ............................................ 1 Description and Taxonomy .................................. 3 Distribution .............................................. 7 Life History and Ecology ................................... 12 Habitat and Ecosystem Description ........................... 22 Reasons for Decline and Current Threats ....................... 25 Conservation Measures .................................... 30 National Wildlife Refuges, State Wildlife Areas, and Other Wetland Conservation Efforts..................................... 36 Ricelands and Agricultural Waterways as Giant Garter Snake Habitat . 40 Recovery Strategy ........................................ 41 RECOVERY .................................................. 44 Objective ............................................... 44 Recovery Criteria ......................................... 44 Giant Garter Snake Delisting Criteria .......................... 46 Recovery Priorities .......................................